class Container {
  static of (value){
    return new Container(value)
  }
  constructor(value){
    this._value =value
  }
  map(fn){
    return Container.of(fn(this._value))
  }
}

class Maybe{
  static of(x){
    return new Maybe(x)
  }
  isNothing(){
    return this._value ===null || this._value ===undefined
  }
  constructor(x){
    this._value =x
  }
  map(fn){
    return this.isNothing() ? this : Maybe.of(fn(this._value))
  }
}

module.exports ={
  Maybe,Container
}